Bailway-teaffic-controlling apparatus



July 29, 1924. 1,503,166 L. V. LEWIS RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Sept. 11, 1919 2 Sheets-Shem. 1

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July 29 1924. 1

L. v. LEWIS RAILWAY TRAFFIC CONTROLfiiNG APPARATUS Original Filed Sept. 11, 1919 2 Sheets-Sheet 2 I N VEN TOR.

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UNITED STATES PATENT OFFICE.

LLOYD V. LEWIS, OF ED'GEVJOOD BORDUGI-l', PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SRWISSVALE, PENNSYLVANIA, A COB- IPOIR-ATION OF PENNSYLVANIA.

RAILTVAY-TRAFFIC-CONTROLLING APPARATUS.

original application filed September 11, 1919, Serial No. 323,168.

6, 1922. Serial No. 599,l4=3.

To all whom it may concern Be it known that I, LLOYD V. LEWIS, a citizen of the United States, residing at Edgewood Borough, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Railway-Tratlic-Controlling Apparatus, of which the following is a specification.

My invention relates to railway traffic controlling apparatus, and particularly to apparatus for controlling the speed of railway cars or trains.

The present application is a division of my copending application filed September 11, 1919, Serial No. 823168, for railway traffic controlling apparatus, now Patent #1,%19,869, June 13, 1922.

A railway signaling system usually includes roadside signals which give restrictive and non-restrictive indications. ll hen an automatic speed controlling systen'i is provided in connection with a signaling system of this kind, the apparatus is usually arranged to permit a train to travel at different speeds depending on the indications given by the signals. A system of automatic control arranged to operatein the manner set forth has one undesirable feature, however, in that it may permit the engineer to disregard hisduty and rely on the automatic apparatus to control the train in the event of dangerous traffic conditions in ad Vance.

This is undesirable, because even if we assume that the automatic apparatus is capable of handling the train equally as well as the en ineer can handle it, it is still a mechanical device and no matter how perfeet it may be, it may fail. On the other hand, we know the engineer is certain to fail,

I at times. The reliability of the engineer depends largely upon his sense of responsibility and physiological fitness, while the automatic devices are independent of such variable conditions. To get the best results from the engineer we must depend upon him and must hold him responsible for the proper observance of signals. 'lli llh this accomplished and thcautomatic control added, we have the latter in reserve if the engineer fails, and the chances of trouble Patent No. 1,419,869, dated June 13,

Eivided and this application filed December 16, 1820, Serial No. 431,116. Renewed November either alone.

To assure, then, that the engineer will attend to his duties if he is physically able to do so, I provide, in combination with an auton'iatic speed control system, means for normally causing the train to come to a stop or to a low speed upon passing a signal which gives a restrictive indication, together with means under the control of the engineer for suppressing such stopping means and permitting the train to proceed in accordance with the indication given by the signal provided that the engineer acknowledges the signal by a suitable manual action while passing the same.

I will describe one form of apparatus embodying my invention, and will then point out the novel features thereof in claims.

1n the accompanying drawings, Fig. 1 is a. view showing one form of train carried apparatus embodying my invention. Fig. 2 is a diagrammatic view showing one form of trackway apparatus which may be employed in connection with the train carried apparatus shown in the preceding views.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 2, the reference characters R and R designate the track rails of a railway, which rails are divided by insulated joints 2 to form blocks A'B, BC, etc. Trailic along the railway is normally in the direction indicated by the arrow. 7

Located adjacent the entrance end of each block is a roadside signal designated by the reference character S with an exponent corresponding to the location. Each signal, as here shown, is of the semaphore type, adapted to indicate stop, caution or proceed according as the semaphore is in the horizontal, inclined or vertical position. The control circuits for these signals form no part of my invention and they are omitted from the drawing, but it is undcrstood that in accordance with usual practic each signal indicates stop when the corresponding block is occupied, caution when the corresponding block is unoccupied and the block next in advance is occupied, and proceed when the corresponding block and the block next in advance are unoccupied. For example, as shown in the drawing the block to the right of location C is occupied by a vehicle V, so that signal S for this block is at stop, signal S for the block next in the rear is at caution, and signal S for the second block in the rear of-the occupied block is at proceed.

Each block is provided with a track circuit comprising as usual the track rails of the block, a source of signaling current connected across the rails adjacent the exit end of the block, and a track relay having a winding connected across the rails adjacent the entrance end of the block. The source of current for each track circuit is the sec ondary of a transformer which is designated T with an exponent corresponding to the location, and the relay for each track circuit is designated by the reference character H with an exponent corresponding to the location.

Each track relay H is of a three-position type, comprising a track winding 4, a second or local winding 5, a rotor 6, and a contact finger 7 operated by the rotor. The track Winding 4 is connected directly with the track rails, and the local winding 5'is connected with a transmission line P to which alternating signaling current is sup plied by a generator 8. Each of these relays, then, responds to reversals of the polarity of the current in the corresponding track circuit with respect to that of the transmission line P, so that the contact linger 7 is swung to the right when the track circuit is of one relative polarity (which I will call normal), and to the left when the track circuit is of the other relative polarity (which I will term reverse). The contact finger occupies an intermediate or ver tical position when the track winding of the relay is de-energized.

The primary of each track transformer T is connected with the transmission line P through the medium of a pole-changer N which is operated by the adjacent signal in such manner that when a signal indicates stop, current of reverse polarity is supplied to the track circuit for the block in the rear, but that when the signal indicates caution or proceed, current of normal polarity is supplied to the track circuit. It follows, then, that the track relay for each block is energized in the reverse direction when the block next in advance is occupied, and in the normal direction when the said block next in advance is unoccupied.

Means are provided for each block for supplying to the rails thereof a second alternating current, which I will term the line circuit current, and which current flows in the same direction in both rails of the block. This current is supplied by a transformer located at the entrance end of the block and designated by the reference character U with an exponent corresponding to the location. The primary of each of these transformers is connected directly with the transmission line P. This current is led into the track rails through connections at the middle points of resistances which are connected across the rails and which are designated by the reference character M with suitableexponents. Three of these resistances are provided for each block, one at the entrance designated M, one at the exit end designated M, and the third at an intermediate point in the block designated M Resistance M for each block is located a distance in the rear of the exit end of the block substantially equal to the maximum braking distance of trains traveling at an interme diate speed, which speed, as hereinafter chosen arbitrarily, is 35 miles per hour. Each block is, therefore, divided by the resistance Ni into a forward section li -M and a rear section M-M The supply of current from each transformer U to the rails of the corresponding block is controlled by contact 7 of the track relay for the block next in advance, this control being such that current is supplied to the rails throughout the entire length of the block when the relay is energized in either direction, and to the rails of only the rear section of the block when the relay is deenergized. For example, when relay H is energized in reverse direction as shown, the line current circuit for block A.B is from the secondary of transformer U through wire 85, contact 'Y86 of relay H wire 87, resistance M', rails of block A'B, resistance M, wire 88, and resistance 24. to the secondary of transformer U lVhen relay H is energized in normal direction the circuit is the same except that it includes relay contact 789 and wire 90. lVhen relay H is de-energized, the line circuit for. this block is from the secondary of transformer U through wire 85, contact 7-9E2. wire 91. resistance M rails of block AB, resistance M, wire 88, and resistance 24 to the secondary of transformer U.

From the foregoing it will be seen that means are provided for each block for supplying two superimposed alternating sig naling currents to the rails thereof, one of which currents flows in opposite directions in the two rails, while the other current flows in the same direction along the rails.

An inductive resistance 53 is included in the secondary circuit of each transformer T, and the non-inductive resistance 24 is included in the secondary circuit of each transformer U, so that the currentsfrom the cuit by track circuit current in the rails two transformers are displaced substantially in phase in the track rails.

Referring now to Fig. 1, the reference character V designates a railway vehicle a car or train), which is represented by an axle and a pair of wheels. Mounted on this vehicle in advance of the forward axle are two pairs of laminated soft iron cores 34 and 34*, the two cores of each pair being located over the two track rails R'- and R respectively. Each core is disposed transversely with respect to the rail. Itis apparent, therefore, that when alternating current flows in either rail, part of the mag-- netic lines of force surrounding such rail will pass through the cores which are directly over the rail, and so will induce an alternating potential in any coils which the cores may carry.

The cores 84, 34 are provided with coils 35 and 36, respectively, and the cores 3 S P, are similarly provided with coils S5" and 86.

The coils 35 and 3,6 are included in a receiving circuit a, the coils being so connected in this circuit that the potentials created in these coils by alternating current flowing in opposite directions in the two rails are additive, while the potentials created in these coils by current flowing in the same directionin the two rails oppose each other and so cause no current in circuit a. Track circuit current from transformers T, therefore, induces current in circuit a,-but the line circuit current supplied by transformers U produces no current in this circuit. I r

Coils 35 and 36 are included in series in a receiving circuit 1), the coils being connected in this circuit in, such manner that the potentials created in these coils by currents flowing in the same direction in the two track rails are additive, but that the potentials created in these coils by cur-- rents flowing in'opposite directions in the two track rails oppose each other. It follows, then, that line circuit current from the transformers U flowing in the track rails will induce current in circuit 7), but that no current will be induced in this cirfrom the transformers T.

v The currents thus induced in the rece1vingclrcuits a and b are utilized to control ythe supply of currents to the twostator windings 37 and 38 of an induction motor relay'F, suitable amplifiers preferably being interposed between the receiving circuits and the relay windings, as indicated in the drawing. Relay F also comprises a rotor member 39 which controls a contact finger 4O biased to normally occupy a vertical or intermediate position whenthe relay is not energized. Inasmuch as the two currents indie track rails are displaced in phase, it follows that the currents in relay windings 37 and 38 will similarly be displaced in phase, so that torque will be exerted on the rotor member 39 in one direction or the other, depending on the relative' instantaneous polarities of the currents in the track. rails. \Vhen the polarity of the track circuit current is normal, relay F is energized in normal direction wherein contact finger 40 is swung to the right; and when the polarity of the track circuit current is reverse, relay F is energized in reverse direction wherein the contact finger is swung to the left. When the track circuit current is cutoff, relay F becomes deenergized so that contact finger 40 drops to its vertical or intermediate position.

Relay F controls two magnets J and J which I will term the high speed magnet and the medium speed magnet respectively. The control of these magnets is such that magnet J is energized when relay F is energized in normal direction (contact 40 to the right), and magnet J is en-- ergized when relay F is energized in reverse direction (contact tO to the left), both magnets being de-energized when the relay is tie-energized. The magnets are controlled by contact 40 through the medium of circuits which are obvious from inspection of the drawing. The magnets J and J control two valves 41 and 41, respectively, which devices in turn control the brake apparatus as will hereinafter appear.

The immediate control of the brakes of vehicle V is effected by a brake application valve K, the control being such that the brakes are applied when the slidingmember 42 of this valve moves to the left from the position shown in the drawing, and that the brakes may be released when the member 42 occupies a position to the right, shown. The ports in valve K and air connections thereto by means of which the brakes ar controlled, are not shown. T he brake valve K is controlled in part by the high and medium speed magnets J and J through the instrumentality of high and medium speed valves L and L and in part by a series of valves 43 43, 43 and 44;. The latter valves are controlled by a crosshead 45 which in turn is governed by a centrifugal device (not shown) driven by a wheel of the vehicle. The brake'valve l; is also controlled in part by a suppressed application valve X, as hereinafter set forth. The chamber to the right of the piston in each of the'valves K, L L, and X is constantly supplied with air pressure by means of a pipe designated 46 with a suitable exponent, which pipes lead to the main reservoir of the air brakesystom.

The control of the three valves 43 by the crosshead 45 is as -follows: All. ofthese and area of the ports which are opened or uncovered by the right-hand end of the plunger varies in accordance with the actual speed of the vehicle. The valve 44 controls a plurality of ports 72 in similar manner.

I will now assume that, when tratlic conditions are as shown in Fig. 2, the vehicle V shown in Fig. 1 enters block A-B of Fig. 2, so that relay F on the vehicle is energized in normal direction; that is, contact finger 40 is swung to the right. The high speed magnet J H is then energized, the medium speed magnet J is de-energized, and the remaining parts of the apparatus shown in Fig. 1 are in the positions in which they are shown in this view, with the exception that the crosshead 45 will be shifted to some point to the left, depending on the actual speed of the vehicle. The sliding member of the high speed valve L is held in the right hand or normal position, because air is supplied to the left-hand face of piston 48 through pipe 46 of suppressed applica tion valve X, the body of the latter valve, and pipe 47 to the piston chamber of valve L. The sliding member of the medium speed valve L is held in the right hand or normal position by air which flows from the main reservoir, through pipe 46 ,valve 41*, pipe 50, cavity 51 in valve X, pipe 52, cavity 53 in valve L and pipe 54 to the piston chamber of valve L Assuming that the speed of the train is less than 65 miles per hour, the sliding member 42 of the brake application valve K is held in its right-hand position, because the piston chamber of this valve is closed and air is admitted to this chamber through a small port 68 in the piston 48 of this valve. The suppressed application valve X is held in the position shown for a similar reason.

I will now assume that while proceeding through block A-B the speed of the vehicle exceeds 65 miles per hour. Crosshead 45 will then open valve 48 thereby opening the piston chamber of the brake application valve K to atmosphere through pipes 56, 57 and 79, and valve 43 The sliding member 42 of valve K will then move to the left owing to the fluid pressure supplied to the right hand face of piston 48 through pipe 46, so that valve 1? will cause an application of the brakes. This movement of member 42 will connect the piston chamber of valve K with atmosphere through pipes 56 and 61, cavity 62, pipe 63, release valve W and port 64. It follows, therefore, that the brakes cannot be released until the engineer presses the plunger of the release valve WV, thus disconnecting the piston chamber of valve K from atmosphere. Operation of valve \V will have no eti'ect, however, until the speed is reduced to less than 65 miles per hour.

I will now assume that the vehicle V passes point B, that is, caution signal S, at a speed greater than 15 miles per hour, and that the engineer takes no action at this point. Relay F will reverse, due to the reversal of polarity of the track circuit current, thereby energizing the medium speed magnet J M and deenergizing the high speed magnet J. The consequent reversal of valve 41 will connect the piston chamber of the. medium speed valve U with atmosphere through pipe 54, cavity 53 of valve L pipe 52, cavity 51' of valve X, pipe 50, valve 41 and exhaust port 55. Valve L will then reverse, that is, its piston and sliding member will shift to the left, and, the speed of the vehicle being above 15 miles per hour, the piston chamber of valve K will exhaust to atmosphere through pipes 56, 57 and 58, cavity 59 of valve L pipe 60, and the low speed valve 43 This will cause the brakes to be applied, and they can be released only by manual operation of valve IV as before. This release can, of course, be effected only after the speed of the vehicle has been reduced to 15 miles per hour or less. The reason for making the device inetl'ective at speeds less than 15 miles per hour is that thereby brake applications which would result from short unavoidable gaps in thecontrolling track circuits, as in passing from one block to another, are avoided. If valve L has a time element of one second the vehicle will be able to bridge a gap of 22 feet in the track circuit at speeds of 15 miles per hour or over.

I will now assume that as the vehicle approaches the caution signal S the engineer pushes the plunger of a penalty valve Z. This action exhausts the piston chamber of valve X to atmosphere through pipe 65, cavity 66 of brake application valve K, pipe 67, and the penalty valve Z. Valve X then reverses, that is, its sliding member moves to the left, and as soon as relay F reverses and magnet J becomes ole-energized, the

J: r piston chamber or valte X is connected wlth atmosphere independently of penalty valve .3; through pipes 65 and 65, cavity 51, pipe 50, valve ll, and the exhaust port Valve Z may then be released, and val e X magnet J remains d e-energized. The

piston chamber of the high speed valve L is then connected with atmosphere through pipe 47, cavity 69 0f valve X, pipe and an orifice 71 of restricted area. Pipe 70 is also opened to atmosphere through one or more of the ports 72, depending on the actual speed of the vehicle, provided that this speed is 35 miles per hour or more. Pipe 47 isconnected, however, with a lill l lv ing reservoir 78, through pipe 7 3 so that valve L does not reverse until after a period of time which depends upon the actual speed of the vehicle. This time interval is so adjusted, by properly proportioning the areas of ports 71 and 72 and the volume of reservoir 73, that the vehicle will be brought to a stop by a brake application due to the reversal of valves L and K, at approximately the same point, irrespective of its initial speed, provided the latter is between 35 and 65 miles per hour.

As'soon as relay F reverses due to the vehicle passing caution signal S magnet J becomes energized, reversing valve 41 to charge a timing reservoir 82 from main reservoir through pipe 46 valve 41 and pipe 75. After valve L shifts to the left,

.the piston chamber of valve L is supplied with fluid pressure from the main reservoir through pipe 46, valve 41, pipe 75, cavity 53 in valve L, and pipe 54. It follows then that valve L remains in its righthand or normal position as long as magnet J remains energized. Y If now the actual speed of the vehicle exceeds 35 miles per hour, brake application valve K will be actuated, because the piston chamber of this valve will be connected with atmosphere through pipes 56 and 57, cavity 7 7 of valve L pipe 7.6 and valve 48 The vehicle .may proceed into block BC, however, at

3.5 miles per. hour or less without incurring an automatic application of the brakes.

I will now assume that the vehicle passes resistance M in block B-@ at a' speed greater than 15 miles per hour, and that the engineer takes no action. Magnet J then becomes tie-energized, thereby opening the piston chamber of valve L to atmosphere through pipe 54, cavity 53 in valve 'L pipe 75, valve 41, pipe 80, and re-' stricted orifice 81. Pipe is also opened to atmosphere through one or more of the ports 78 depending on the speed of the vehicle. Owing to the timing reservoir 82 which is connected with pipe 75, valve U will not shift until the expiration of an interval of time which depends upon the. actual speed of the vehicle, so that the vehicle will be brought to a stop due to the reversal of valves L and K at approximately the same point from any initial speed between 35 and 15 miles per hour. When valve L shifts the piston chamber of valve K will be connected with atmosphere through pipes 56,

57 and 58, cavity 59 in valve L pipe 82, cavity 83 of valve X, pipe 84, and a penalty valve Z. An automatic application of the brakes will, consequently, ccur regardless of the speed of the vehicle. If, however, the engineer operates the plunger of valve Z while passing resistance M the exhaust passage just traced will be closed at valve Z, and air pressure will build up in the chamber of valve Z to hold this valve closed as long as X or L are reversed; hence the brakes will not be applied unless the speed of the vehicle exceeds 15 miles per hour. In the event that the speed does exceed this value, the piston chamber of valve K will be opened to atmosphere through pipes 56, 57 and 58, cavity 59 of valve L pipe 60, and low speed valve 43?.

I will now assume that while the vehicle is moving at less than 15 miles per hour, relay F becomes energized in normal direction. The consequent energization of magnet J H will cause air to be supplied to the piston chamber of valve X, through pipe 46", valve 41, pipe 50, cavity 51, pipe 65 and pipe 65. Valve X will, therefore, return plied to the piston chamber of valve L through valve 41, pipe 50, cavity 51, pipe 52, cavity 53 and pipe 54. The, parts of the apparatus will thus berestored to the positions in which they are shown in the drawing.

One important feature of the structure shown in Fig. 1 is the cavity 66 of valve K which is included in the path from the piston chamber of valve X to atmosphere through penalty valve Z. When valve K moves to brake-applying position, this path is closed at chamber 66, and so the engineer is unable to suppress a brake application result'sng from his failure to observe and act plication is initiated.

It will be seen from the foregoing, that I have provided means for causing an auto matic application of the brakes upon passing a caution s gnal, unless the speed of the vehicle is 15 miles per hour or less, and means under the control of the engineer for sup pressing such automatic brake application and permitting the vehicle to proceed at a speed corresponding to the indication given by the s gnal, provided that the engineer takes the proper action while passing the caution signal. Similarly, means are provided for causing an automatic application of the brakes upon approaching a stop signal, together with means under the control of the engineer for suppressing such automat c application and permitting the vehicle to proceed at a low speed up to and 'upon a caution signal, after such brake appast the stop signal, provided that the en gineer takes the proper action at the proper time.

Although I have herein shown and described only one form of apparatus ei'nbodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Railway traltic controlling apparatus compris'ng a l'iigh speed valve and a medium speed valve carried on a vehicle, means on the vehicle controlled by said valves and by the speed of the vehicle for applying the ln'akes when both valves are in normal position and the vehicle exceeds a fixed high speed limit, also when the high speed valve is m reversed pos tion and the medium speed valve is in normal position and the vehicle exceeds a medium speed limit, also when the medium speed valve is in reversed position and the vehicle exceeds a low speed lim't, means on the vehicle controlled from the trackivay for holding both valves in normal position under proceed traflic conditions and for reversing the medium speed valve when trailic conditions change from proceed to caution, and manually controllable means on the vehicle, for preventing said medium speed valve from reversing and permitting said high speed valve to reverse when tra'tfic condltions change from proceed to caution.

2. Railway tral'lic controlling apparatus comprising a medium speed valve and a high speed valve carried by a vehicle and maintained in normal positions under clear traffic conditions, means for reversing the medium speed valve upon a change to a less favorable trafiic condition, manually controllable means on the vehicle for preventing reversal of the medium speed valve and causing reversal of the high speed valve upon such change of traflic condition, and means con trolled by said valves for causing certain speed restrictions when the medium speed valve is reversed, and less-severe speed restrictions when the high speed valve is re-v versed and the medium speed valve is in normal position.

3. Railway traflic controlling apparatus comprising a medium speed valve and a high speed valve carried by a vehicle, means controlled trom the trackway tor reversing the medlum speed valve upon a change from a 'more favorable to a less favorable trafiic hicle for causing certain speed restrictions when the medium speed valve is reversed and less severe speed restrictions when the high speed valve is reversed and the medium speed valve is in normal position.

l. Railway traflic controlling apparatus comprising a medium speed valve and'a high speed valve carried by a vehicle and maintained in normal positions under clear traflic conditions, means for reversing the medium speed valve upon a change to caution t 'ar'iic condition, manually controllable means on the vehicle for preventing reversal of the medium speed valve and causing reversal of the high speed valve when such change of traiiic condition occurs, and means controlled by said valves and by the speed of the vehicle for causing certain speed re strictions when the medium speed valve is reversed and less severe speed restrictions when the high speed valve is reversed and the medium speed valve is in normal position.

Railway trafiic controlling apparatus 7 of the high speed valve when said change 01": trafiic conditions occurs, and means controlled by the two first-mentioned valves for causing certain speed restrictions when the medium speed valve is reversed and less severe speed restrictions when the high speed valve is reversed and the medium speed valve is in normal position.

6. Railway traffic controlling apparatus comprising a medium speed valve anda high speed valve carried by a vehicle, means controlled from the trackway for reversing the medium sueed valve upon a change from a more "favorable to a less favorable traflic'condition, a suppressed application valve also carried by the vehicle and normally occupying an inactive position, manually controllable means on the vehicle for reversing said suppressed application valve prior to the said change of t-raflic condition, means controlled by said suppressed application valve when in reversed position for preventing reversal of the medium speed valveand for causing reversal of the high speed valve upon the expiration of an interval of time inversely proportional to the actual speed of the vehicle after the said change of traiiic conditions occurs, and means controlled by the two first-mentioned valves for causing certain speed restrictions when the medium speed valve is reversed and less severe speed restrictions when the high speed valve is reversed and the medium speed valve is in normal position.

7. Railway traffic controlling apparatus comprising a medium speed 'alve and a high speed valve carried on a vehicle and maintained in normal positions under proceed trafiic conditions, means for reversing the medium speed valve upon a change from proceed to caution traflic condition, a suppressed application valve also ca rried by the vehicle and normally occupying an inactive position, manually controllable meanson the vehicle for reversing said suppressed appli cation valve prior to said change of traffic conditions, means controlled by said suppressed application valve when reversed for preventing reversal of the medium speed valve and causing reversal of said high speed valve when said change of traffic condition occurs, means for reversing said medium speed valve upon a change from caution to stop tralfic conditions; means con trolled by the first-mentioned valves for causing certain speed restrictionswhen the medium speed valve is reversed and the high speed valve is normal, for causing less severe speed restrictions when the high speed valve is reversed and the medium speed valve is normal, and for applying the brakes when both valves are reversed and the suppressed application valve is also reversed; and manually operable means on the vehicle for preventing such brake application at low speed when all three valves are reversed.

8. Railway traific controlling apparatus comprising vehicle carried means controlled from the trackway for automatically applying the brakes regardless of the speed of the vehicle upon a change from a more favorable to a less favorable traffic condition, means for delaying such application for an interval of travel which depends on the speed of the vehicle, and means on the vehicle -for preventing such automatic brake application if the engineer takes suitable action during said interval.

9. Railway trailic controlling apparatus comprising vehicle carried means controlled from the trackway for automatically applying the brakes regardless of the speed of the vehicle upon a change from caution to stop traffic conditions, means for delaying such application for an interval of travel which depends on the speed of the vehicle, and means on the vehicle for preventing such automatic brake application if the engineer takes suitable action during (said interval.

In testimony whereof I aflix my signature.

LLOYD V. LEWIS. 

